I just just tried to reply to two comments. One using connect and I got a 502. The other using the web browser and it is still waiting. We will see if a new post will work I guess.
I think Lemmy is going through a lot of growing pains right now on a few fronts. Hopefully things will smooth out in the near future. If you like what you see here, consider donating to an instance/app so that people can develop this wonderful thing further.
Okay so it appears that the post/reply system gets hung up while processing, but the post/reply/edits do go through. (Same thing is happening on the Memmy iOS/iPadOS app.)
On the web, after a few seconds of watching the button throbber spin, you can reload / refresh the page and your comment will appear. (In the Memmy app you can wait until the json error appears, then select "Cancel" and your comment/edit will appear.)